Kprobes: print details of kretprobe on assertion failure

In certain cases like when the real return address can't be found or when
the number of tracked calls to a kretprobed function is less than the
number of returns, we may not be able to find the correct return address
after processing a kretprobe.  Currently we just do a BUG_ON, but no
information is provided about the actual failing kretprobe.

Print out details of the kretprobe before calling BUG().

Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index f2646070037..850ee871e35 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -157,6 +157,16 @@ struct kretprobe_instance {
         struct task_struct *task;
 };
 
+static inline void kretprobe_assert(struct kretprobe_instance *ri,
+        unsigned long orig_ret_address, unsigned long trampoline_address)
+{
+        if (!orig_ret_address || (orig_ret_address == trampoline_address)) {
+                printk("kretprobe BUG!: Processing kretprobe %p @ %p\n",
+                                ri->rp, ri->rp->kp.addr);
+                BUG();
+        }
+}
+
 extern spinlock_t kretprobe_lock;
 extern struct mutex kprobe_mutex;
 extern int arch_prepare_kprobe(struct kprobe *p);